麦草畏降解菌株Ochrobactrum sp.3-3的分离鉴定及其降解特性  

Isolation and identifi cation of dicamba-degrading bacterium Ochrobactrum sp.3-3 and investigation of its degradation characteristics

作　　者：于林鹭 姚利[1] 李娜[1] 褚翠伟 何健[1] 

机构地区：[1]南京农业大学生命科学学院,农业部农业环境微生物工程重点开放实验室,南京210095

出　　处：《应用与环境生物学报》2017年第2期283-288,共6页Chinese Journal of Applied and Environmental Biology

基　　金：国家自然科学基金项目(3157010 5);教育部新世纪优秀人才项目(NCET-13-0861)资助~~

摘　　要：麦草畏是理想的抗除草剂转基因工程的靶标除草剂;发掘新的麦草畏高效降解菌株和基因具有非常重要的理论和应用价值.从南京土壤样品中分离到一株麦草畏高效降解菌株,命名为3-3.根据生理生化特征和16S r DNA序列相似性分析,将其初步鉴定为苍白杆菌属(Ochrobactrum sp.).菌株3-3在48 h内完全降解100 mg/L的麦草畏.该菌株降解麦草畏的最适温度为30℃,最适p H为7.0.代谢产物高效液相和质谱鉴定结果表明该菌株降解麦草畏的起始步骤是脱甲基,形成没有除草活性的3,6-二氯水杨酸(DCSA).菌株粗酶液只在NADH存在时才有麦草畏脱甲基酶活性.PCR扩增和该菌基因组生物信息学分析表明该菌株没有已报道的麦草畏脱甲基酶基因DMO、Mtv及Dmt或其同源序列.总之,本研究首次分离筛选到苍白杆菌属的麦草畏降解菌,且该菌可能存在一个新的氧化酶类麦草畏脱甲基酶基因.Dicamba is a kind of synthetic auxin herbicide. Because of its high efficiency, broad weed control spectrum, and low mammalian toxicity, dicamba is considered to be a suitable target herbicide for the generation of herbicide-resistant transgenic crops. Thus, new dicamba-degrading strains, as well as gene resources, have very important application in herbicide-resistant transgenic engineering. In this study, a bacterial strain 3-3 having high efficiency to degrade dicamba was isolated from a soil sample from Nanjing. The strain was preliminary identified as Ochrobactrum sp. according to its physiological and biochemical characteristics and 16S rDNA gene sequence analysis. Strain 3-3 could completely degrade 100 mg/L dicamba within 48 h. The optimal temperature and pH for dicamba degradation were 30 ℃ and 7.0, respectively. The high-performance liquid chromatography and tandem mass spectrometry analysis indicated that the first step of dicamba degradation in strain 3-3 was demethylation to generate the herbicidally inactive metabolite 3,6-dichlorosalicylic acid. The crude enzyme of strain 3-3 showed dicamba demethylase activity only in the presence of NADH. Polymerase chain reaction amplification and genomic bioinformatic analysis of the strain indicated that the reported dicamba demethylase genes DMO, Mtv, and Dmt or their homologous sequences were not found in the genome of the strain. These data suggested that a new NADH-dependent dicamba demethylase gene was present in strain 3-3. In conclusion, to our knowledge, this is the first study to report a new dicamba-degrading strain Ochrobactrum sp. 3-3, and to show that this strain had a new NADH-dependent demethylase gene.

关 键 词：麦草畏 生物降解 苍白杆菌属(Ochrobactrum sp.) 脱甲基酶 

分 类 号：X172[环境科学与工程—环境科学]